论文标题
K频段光谱的凉爽巨人的新温度和金属尺度
New Temperature and Metallicity Scale of Cool Giants from K-band Spectra
论文作者
论文摘要
我们在这里提出了用于酷巨人的定量诊断工具，这些工具在$ k $ band中采用低分辨率的近红外光谱仪用于出色的人群研究。在这项研究中，总共使用了260个凉爽的巨人（用X射手观察到177颗恒星，使用NIFS观察到83颗恒星），涵盖了更宽的金属性范围。我们测量了一些选定的重要$ k $频段光谱功能的等效宽度，例如na i，fe i和$^{12} $ co在降低光谱分辨率（r $ \ sim $ 1200）之后，以使用基本参数（例如有效温度和金属性）来研究光谱行为。我们得出经验关系，以使用$^{12} $ CO的第一反过度频带测量有效温度，为2.29 $ $ m $ m和2.32 $μ$ m，并显示了这些相关性的详细定量金属性依赖性。我们发现，基于太阳邻化星的经验关系可以在评估$ t_ {eff} $的金属贫困或金属丰富的恒星中融合大量不确定性。此外，我们探索所有光谱线以建立经验关系，并发现Na I和$^{12} $ CO组合的二次拟合在2.29 $ $ $ m上的线条可在[$ fe/h $ \ leq $ \ $ 0.4 dex上提供一个line for and line and line for a line and line and line and a in line and a in line and a in line and a in line and a in line and a in line and a in line and a in line and a in line and line a in line and a in line and a in line and for a in line an [$ fe/h $] $ \ geq $ 0.0 dex。
We present here quantitative diagnostic tools for cool giants that employ low-resolution near-infrared spectroscopy in the $K$-band for stellar population studies. In this study, a total of 260 cool giants (177 stars observed with X-shooter and 83 stars observed with NIFS) are used covering a wider metallicity range than in earlier works. We measure equivalent widths of some of the selected important $K$-band spectral features like Na I, Fe I, and $^{12}$CO after degrading the spectral resolution (R $\sim$ 1200) to investigate the spectral behavior with fundamental parameters (e.g. effective temperature and metallicity). We derive empirical relations to measure effective temperature using the $^{12}$CO first-overtone band at 2.29 $μ$m and 2.32 $μ$m and show a detailed quantitative metallicity dependence of these correlations. We find that the empirical relations based on solar-neighborhood stars can incorporate large uncertainty in evaluating $T_{eff}$ for metal-poor or metal-rich stars. Furthermore, we explore all the spectral lines to establish the empirical relation with metallicity and find that the quadratic fit of the combination of Na I and $^{12}$CO at 2.29 $μ$m lines yields a reliable empirical relation at [$Fe/H$] $\leq$ $-$0.4 dex, while a linear fit of any line offers a good metallicity scale for stars having [$Fe/H$] $\geq$ 0.0 dex.
